
function unified_inventory.get_formspec(player, page)
	if not player then
		return ""
	end
	local player_name = player:get_player_name()
	unified_inventory.current_page[player_name] = page
	local pagedef = unified_inventory.pages[page]

	local formspec = "size[14,10]"
	local fsdata = nil

	-- Background
	formspec = formspec .. "background[-0.19,-0.25;14.4,10.75;ui_form_bg.png]"
	-- Current page
	if unified_inventory.pages[page] then
		fsdata = pagedef.get_formspec(player)
		formspec = formspec .. fsdata.formspec
	else
		return "" -- Invalid page name
	end

	-- Main buttons
	for i, def in pairs(unified_inventory.buttons) do
		if def.type == "image" then
			formspec = formspec.."image_button["
					..(0.65 * (i - 1))..",9;0.8,0.8;"
					..minetest.formspec_escape(def.image)..";"
					..minetest.formspec_escape(def.name)..";]"
		end
	end

	if fsdata.draw_inventory ~= false then
		-- Player inventory
		formspec = formspec.."listcolors[#00000000;#00000000]"
		formspec = formspec .. "list[current_player;main;0,4.5;8,4;]"
	end

	if fsdata.draw_item_list == false then
		return formspec
	end

	-- Controls to flip items pages
	local start_x = 9.2
	formspec = formspec .. "image_button["..(start_x + 0.6 * 0)..",9;.8,.8;ui_skip_backward_icon.png;start_list;]"
	formspec = formspec .. "image_button["..(start_x + 0.6 * 1)..",9;.8,.8;ui_doubleleft_icon.png;rewind3;]"
	formspec = formspec .. "image_button["..(start_x + 0.6 * 2)..",9;.8,.8;ui_left_icon.png;rewind1;]"
	formspec = formspec .. "image_button["..(start_x + 0.6 * 3)..",9;.8,.8;ui_right_icon.png;forward1;]"
	formspec = formspec .. "image_button["..(start_x + 0.6 * 4)..",9;.8,.8;ui_doubleright_icon.png;forward3;]"
	formspec = formspec .. "image_button["..(start_x + 0.6 * 5)..",9;.8,.8;ui_skip_forward_icon.png;end_list;]"

	-- Search box
	formspec = formspec .. "field[9.5,8.325;3,1;searchbox;;]"
	formspec = formspec .. "image_button[12.2,8.1;.8,.8;ui_search_icon.png;searchbutton;]"

	-- Items list
	local list_index = unified_inventory.current_index[player_name]
	local page = math.floor(list_index / (80) + 1)
	local pagemax = math.floor(
		(#unified_inventory.filtered_items_list[player_name] - 1)
			/ (80) + 1)
	local item = {}
	for y = 0, 9 do
	for x = 0, 7 do
		local name = unified_inventory.filtered_items_list[player_name][list_index]
		if minetest.registered_items[name] then
			formspec = formspec.."item_image_button["
					..(8.2 + x * 0.7)..","
					..(1   + y * 0.7)..";.81,.81;"
					..name..";item_button_"
					..name..";]"
			list_index = list_index + 1
		end
	end
	end
	formspec = formspec.."label[8.2,0;Page:]"
	formspec = formspec.."label[9,0;"..page.." of "..pagemax.."]"
	formspec = formspec.."label[8.2,0.4;Filter:]"
	formspec = formspec.."label[9,0.4;"..unified_inventory.activefilter[player_name].."]"
	return formspec
end

function unified_inventory.set_inventory_formspec(player, page)
	if player then
		local formspec = unified_inventory.get_formspec(player, page)
		player:set_inventory_formspec(formspec)
	end
end

--apply filter to the inventory list (create filtered copy of full one)
function unified_inventory.apply_filter(player, filter)
	local player_name = player:get_player_name()
	local size = 0
	local lfilter = string.lower(filter)
	if not pcall(function() ("technic:test"):find(lfilter) end) then
		-- Filter is invalid
		lfilter = ""
	end
	unified_inventory.filtered_items_list[player_name]={}
	if lfilter:sub(1, 6) == "group:" then
		local groups = lfilter:sub(7):split(",")
		for name, def in pairs(minetest.registered_items) do
			if def.groups then
				local all = true
				for _, group in ipairs(groups) do
					if not (def.groups[group] and (def.groups[group] > 0)) then
						all = false
						break
					end
				end
				if all then
					table.insert(unified_inventory.filtered_items_list[player_name], name)
					size = size + 1
				end
			end
		end
	else
		for name, def in pairs(minetest.registered_items) do
			if (not def.groups.not_in_creative_inventory or
			   def.groups.not_in_creative_inventory == 0)
			   and def.description and def.description ~= "" then
				local lname = string.lower(name)
				local ldesc = string.lower(def.description)
				if string.find(lname, lfilter) or string.find(ldesc, lfilter) then
					table.insert(unified_inventory.filtered_items_list[player_name], name)
					size = size + 1
				end
			end
		end
	end
	table.sort(unified_inventory.filtered_items_list[player_name])
	unified_inventory.filtered_items_list_size[player_name] = size
	unified_inventory.current_index[player_name] = 1
	unified_inventory.activefilter[player_name] = filter
	unified_inventory.set_inventory_formspec(player,
			unified_inventory.current_page[player_name])
end

function unified_inventory.items_in_group(groups)
	local items = {}
	for name, item in pairs(minetest.registered_items) do
		for _, group in pairs(groups:split(',')) do
			if item.groups[group] then
				table.insert(items, name)
			end
		end
	end
	return items
end
